1. Field of the Invention
The present invention relates to an organic or inorganic coating composition containing a photocatalyst partially covered thereon with calcium phosphate.
2. Description of the Prior Art
A coating though depending on its use yellows or deteriorated with time after application, due to the adhesion of oil in dirt from the hands, moisture in the air, oxidation, photodecomposition etc.
Accordingly, an anti-fungus agent is incorporated into a coating to improve the durability of its film and to maintain its appearance.
For example, JP 8-259891A (1996) discloses the art of incorporating a powder having photocatalytic functions into a silica coating. As the powder having photocatalytic functions, mention is made of titanium oxide, zirconium oxide, zinc oxide, strontium titanate, tin oxide, tungsten oxide, iron oxide and bismuth oxide, and it is described in the Examples therein that e.g. deodorization and antibacterial effects are achieved by incorporating titanium oxide into a film.
JP 5-305691A (1993) describes a hydrophilic film having a film containing silica and an inorganic material with an average particle diameter of 5 .mu.m or less selected from titanium dioxide, chromium oxide and iron oxide, said film further containing at least silica thereon.
WO 96/29375 discloses a photocatalytic hydrophilic film comprising silica and a photocatalytic material selected from TiO.sub.2, ZnO, SnO.sub.2, SrTiO.sub.3, WO.sub.3, Bi.sub.2 O.sub.3 and Fe.sub.2 O.sub.3.
JP 10-237357A (1998) (published after the priority date of the present patent application) describes a photocatalytic hydrophilic coating composition consisting of a solution containing crystalline titanium oxide particles, tungsten chloride and tetrahydrofuran.
Further, as a material for forming a hydrophobic surface, JP 10-237431A (1998) (published after the priority date of the present patent application) describes a water-repellent material containing photocatalyst oxide particles such as titanium oxide etc., silicone and a water-repellent fluorine resin.
However, even if the photocatalyst described in these publications is contained in a film, there are also cases where effects such as deodorization and antibacterial effects are inadequate, and it is desired to develop a coating having higher durability and appearance-retention performance for a prolonged period of time.
In addition, if an organic coating is used as a coating component, the organic coating component comes into direct contact with TiO.sub.2 etc., so there is also the problem of coating deterioration.